The proposed work will study the relationship between field defects in low vision patients and performance on everyday tasks important to mobility, reading, and successful use of optical aids. We will also develop procedures for scoring ordinary visual field maps that are specific to these tasks. The study will concentrate on four visual abilities that are expected to mediate performance on the specific tasks: 1) detecting, 2) finding, 3) scanning stationery objects, and 4) tracking moving objects. Our performance measures are 1) a self-report questionnaire designed to probe visual function in everyday circumstances, 2) direct observation of the subject's visual function both indoors and outdoors, 3) mobility on an indoor test course, 4) reading ability, and 5) psychophysical measures of scanning and tracking performance. The long-term objectives are to 1) provide a better understanding of the relationships between field defects and visual performance, 2) describe the factors that determine successful use and acceptance of low vision aids, and 3) provide clinicians and rehabilitation professionals with tools that can better predict the client's functioning in everyday life.